Kidde Nighthawk CO Detector: Why Single Beep Every Day ?

["Robert11" <rgsrose@xxxxxxxxx>]

Hello:

Have a new Kidde Nighthawk plug-in CO detector (Model 900-0076 AC) for
house.
Seems to work fine, but -

About every other day or so, it gives a single beep.
Never more than one beep, and never more than once a day.

Replaced the backup battery with a brand new one.
The unit is plugged into the wall socket, so is working off of the AC,
normally.
The outlet is relatively close to floor.  Floor has a rug.

Any idea why this single beep may be occuring ?   Might it be dust from the
rug ?

Is it systamatic for these types of gadgets ?

No big deal, but certainly annoying and disconcerting.

Any thoughts on would be appreciated.

Thanks,
Bob